Contact brush unit for an electrical machine, particularly for a slip-ring electrical machine

ABSTRACT

A contact brush unit comprises a device for replacement of a worn-out brush without stopping the operation of the machine. The device includes a sleeve, mounted around a brush holder and secured at one end to a current supply bar of the machine so that the portion of the brush holder, received inside the current supply bar, is pressed by the sleeve against this bar. The unit also includes a means for raising the brush selectively off the rotor contact member, e.g. a slip ring, such means being springmounted on the stem and freely passing through the other, opposite end of the sleeve, the last-mentioned end of the sleeve having an edge portion adapted to retain thereon the brushraising means in an abutted position, when the brush is to be replaced, whereby the sleeve and the brush holder can be jointly removed from the current supply bar during operation of the machine.

United States Patent [72] Inventors Alexandr Abramovich Chigirinshy' Appl. No. Filed Patented ulitsa Kuibysheva, II, kv. 8,

Evgeny Khalmovieh Glider, prospekt Ordzhonikidze, I8, kv. 55; Oleg Borisovlch Gradov, ulitsa Kosiora, 6, kv. 1; David Bentsionovich Kapnman, ulltsa FrantIsheka-Krala 49, kv. 54; Boris Leonldovich Konovalov, ulitsa l2 Aprelya, l0, kv. l6; Boris Bolkovlch Splvak, ulltsa Kosiora, 56, kv. 55; Vasily Semenovlch Klldishev, ulitsa Plekhanovskaya, 41/43,

' kv. 55; Ivan Eliseevich MaKogonenko,

ulltsa Metallistor, 8, kv. 90; Ivan Terentlevich Flllpenko, Saltovskoe shosse, 57, kv. 16, all of Kharkov, U.S.S.R.

10,727 Feb. 12, I970 Dec. 14, 1971 CONTACT BRUSH UNIT FOR AN ELECTRICAL MACHINE, PARTICULARLY FOR A SLIP-RING ELECTRICAL MACHINE 6 Claims, 6 Drawing Figs.

US. Cl 310/240, 310/247 Int. Cl. I10 Ir 39/42 Field of Search 310/247, 239, 240, 242, 245

Primary Examiner-D. X. Sliney Assistant Examiner-B. A. Reynolds Attorney-Waters, Roditi, Schwartz & Nissen ABSTRACT: A contact brush unit comprises a device for replacement of a worn-out brush without stopping the operation of the machine. The device includes a sleeve, mounted around a brush holder and secured at one end to a current supply bar of the machine so that the portion of the brush holder, received inside the current supply bar, is pressed by the sleeve against this bar. The unit also includes a means for raising the brush selectively off the rotor contact member, e.g.

' a slip ring, such means being spring-mounted on the stem and freely passing through the other, opposite end of the sleeve, the last-mentioned end of the sleeve having an edge portion adapted to retain thereon the brush-raising means in an abutted position, when the brush is to be replaced, whereby thesleeve and the brush holder can be jointly removed from the current supply bar during operation of the machine.

Patented Dec. 14, 1971 2 Sheets-Sheet 1 Patented Dec. 14, 1971 2 Sheets-Sheet 2 CONTACT BRUSH UNIT FOR AN ELECTRICAL MACHINE, PARTICULARLY FOR A SLIP-RING ELECTRICAL MACHINE The present invention relates to electrical machines and, more particularly, it relates to contact brush units for electrical machines, preferably, slipring machines, and it can be employed, for example, in high-power turbine-generator sets.

As present electrical machines often have a considerable power capacity, even a short-time delay in the operation of such machines brings about substantial economic losses. In this connection, substantial effort has been devoted recently to the development of such designs of contact brush units, which will make it possible to replace a wornout brush without the necessity of stopping the machine.

Contact brush assemblies are known which provide for replacement of a wornout brush with sufficient safety and without the use of any additional protection means during operation of an electrical machine.

Known in the art are contact brush units for an electrical machine, including a brush-having connected thereto a stem and a pressure member, a brush holder mounted on a current supply bar of the machine and an insulating means in the form of a lever, providing for replacement of a wornout brush without stopping the machine.

However, this known structure is of a relatively great size, whereby its application involves either increasing the diameter of the associated slipring, or else reducing the number of the contact brushes arranged about the ring. Besides, this known contact brush unit does not give any indication of the degree to which the brush has worn in operation. The contact brush holder is removed without the brush having been raised off the slipring beforehand, which might lead to undesired generation of sparks, as the holder is raised and removed.

Additionally, the brush replacement operation is not convenient enough, since when the lever is pressed down, the entire brush holder has to be held by the operator in his hands, which might lead to either the brush holder or the edge of the brush accidentally touching the rotating slipring.

A device is also known for incorporation in a contact brush unit, which provides for raising the brush and retaining it in the raised position, as the brush is being replaced. HOwever, this device is also bulky and does not ensure adequate safety and swiftness of the brush replacement operation.

It is an object of the present invention to eliminate the above-mentioned disadvantages.

The main object of the present invention is to provide a contact brush unit for an electrical machine, e.g. for a turbinegenerator set, which will provide for facilitated replacement of a worn-out brush, for adequately safe operation of removing the contact brush unit from the current supply bar, with the brush having been raised off the contact means of the rotor beforehand and retained with this raised position, for positive retaining of the brush-raising means in respect to the brush holder, as well as for indicating the degree to which the brush has worn out in operation.

These objects are accomplished in a contact brush unit for an electrical machine, particularly, for a slipring electrical machine, comprising a brush connected to a stem, this stem receiving thereabout a compression spring adapted to effect engagement between the brush and the contact means of the rotor of the machine; means cooperating with the stem and adapted to effect selective raising of the brush and retaining the brush in a raised position, a brush holder adapted to be secured to a current supply bar of the machine, insulating means for replacement of the brush in operation of the machine, in which contact brush unit, in accordance with the present invention, said means for replacement of said brush includes a hollow sleeve mounted at least partly about said brush holder and adapted to be secured by its first end to said current supply bar, so that a portion of said brush holder, received inside said current supply bar, is pressed by said sleeve against said current supply bar, whereas said means for selective raising of said brush is spring-mounted on said stem and passes freely through the second end of said sleeve, opposing said first end, said second end of said sleeve having an edge portion adapted to retain thereon said brush-raising means in an abutted position, when said brush is to be replaced, whereby said sleeve and said brush holder can be removed as a body from said current supply bar.

According to a preferred embodiment of the present invention, it is expedient for said brush holder to be provided with a stop member against which said brush-raising means is adapted to abut in a retained position, and for a resilient member to be interposed between the portion of said'brush holder, received inside said current supply bar, and said sleeve, the latter pressing upon said brush holder through said resilient ember. In this way any accidental loosening of said sleeve in respect of said brush holder in operation of the machine is prevented, and dependable electric contact between the current supply bar and the brush holder is ensured, with the brush-raising means being retained in the operating position thereof.

It is further expedient for the end of said stern, opposite to said brush, to carry an element which should lower together with the stem, as the brush gets gradually worn out in operation, whereby this element would follow the degree of the wearing out of the brush, this element being further adapted to abut said brush-raising means, when the brush is worn out beyond an admissible extend, whereby any further lowering of the brush is prevented.

A contact brush unit, constructed in accordance with the present invention, has been found to attain the aforementioned aims and objects, and, besides, to feature a simplicity of structure, a relatively small size and a dependable performance.

The present invention will be better understood from the following detailed description of a preferred embodiment thereof, with due reference being had to the accompanying drawings wherein:

FIG. 1 is a longitudinally sectional view of a contact brush unit in accordance with the present invention;

FIG. 2 is a top plan view of the contact brush unit, in FIG. 1;

FIG. 3 shows schematically the same contact brush unit, as shown in FIG. 1, in which the brush-raising means is in its operating position, and the brush is unworn;

FIG. 4 shown s schematically the same contact brush unit, but with the brush worn to a full permissible extent;

FIG. 5 shows schematically the same brush unit, in which the brush-raising means is in its raised position and is retained against the upper end edge of the sleeve; and

FIG. 6 shows schematically the same contact brush unit, removed bodily from the current supply bar.

Referring now in particularly to the appended drawings, it is seen from FIG. I that the contact brush unit, embodying the present invention, comprises a brush holder structure I the lower portion of which is a hollow housing 2, rectangular in cross section and having an external cylindrical flange 3. The housing 2 has an internal opening receiving thereinside a contact brush 4. A resilient shock-damping washer 5 is mounted on top of the brush 4, and an elongated step 6 is connected to the brush 4 and bears on the washer 5 from above.

Mounted above the brush holder structure and connected therewith is an apertured stop member 7, with the stem 6 freely passing through the aperture in member 7. Mounted about the stem 6, intermediate the shock absorbing washer 5 and the apertured stop member 7 is a compression spring 8 which is adapted to ensure positive engagement between the bottom end of the brush 4 and the slipring 9 of the rotor of the associated motor during operation of the motor. The brush holder structure 1 supports a device enabling replacement of the brush in operation of the motor, the device including a hollow sleeve 10 made of an electrically insulating material.

A threaded bottom end portion of the sleeve 10 is screwed into a threaded opening of a current supply bar I I and presses the housing 2 of the brush holder structure 1 against an internal shoulder in the bar 11, the pressure being transmitted via a resilient annular member 12. Passing freely through the top end of the hollow sleeve is a member 13 for selectively raising the brush 4 and retaining the same in a raised position, the cross-sectional shape of the member 13 corresponding to the internal cross-sectional shape of the opening in the sleeve 10, through which opening the member 13 extends (see FIG. 2).

The member 13 is also made of an electrically insulating material, and a compression spring 14 (which is substantially weaker than the spring 8) holds the member 13 against the stop member 7, the spring 14 being received about the stem 6 and compressed in operation between the bottom flange of the member 13 and an indicating element 15 mounted on the end portion of the stem 6, opposite to the end portion thereof connected to the brush 4. Also shown in FIG. 1 is a flexible metal conductor 16 providing positive electric connection between the brush 4 and the brush holder 1. Ventilation ports 17 are provided in the sleeve 10. The housing 2 of the brush holder structure 1 has a groove 18 therein, the groove 18 defining a desired setting of the brush 4 relative to the supply bar ll in an assembled state of the contact brush assembly.

As has been already mentioned, in an operative state of the herein disclosed contact brush unit the latter is connected with the supply bar 11 by the threaded engagement, of the bar 1] with the sleeve 10 (FIG. 3). The brush-raising member 13 is held against the stop member 7 of the brush holder structure I and retained thereon, preventing in this manner any accidental loosening (by unscrewing action) of the sleeve 10 with respect to the bar 11 and the brush holder structure 1, the compression of the resilient member 12 ensuring positive electric contact between the current supply bar 11 and the housing 2 of the brush holder structure 1. The compression of the spring 8 is responsible for positive contact of the brush 4 with the slipring 9. When the brush 4 is new, the indicating element 15 is in its uppermost position, i.e. the element 15 is raised well above the upper extremity of the brush-raising member 13. As the brush 4 wears in the course of operation of the associated electrical machine, the stem 6 together with the brush 4 and the indicating element 15 gradually lower, as shown in FIG. 4; when the brush 4 becomes worn beyond a permissible extent, the indicating element 15 abuts against the bottom of the member 13 and thus prevents any further lowering of the stem 6 with the brush 4. Thus, the position of the indicating element 15 is clearly indicative of the degree to which the brush 4 is worn, In order to replace a worn brush, the brush raising member 13 is raised manually, until it clears the sleeve 10, whereafter it is rotated about the stem 6 through a corresponding angle and released to abut against the top edge 19 of the sleeve 10 under the compression force of the spring 8. In this manner the brush 4 is retained in its raised position, and the sleeve 10 may be now unscrewed manually from the current supply bar 11, whereafter the contact brush assembly can be removed as a body, as is shown in FIG. 6. With the contact brush assembly being removed in the above-described manner, any accidental contact between the contact brush holder and the contact means (the slipring) of the rotor, or between the edge of the brush and the contact means of the rotor, is positively prevented. After the worn brush has been replaced, the contact brush assembly may be put back and secured to the current supply bar, the procedure being the reverse of the one described.

We claim:

1. A contact brush unit for an electrical machine, particularly, for a slipring electrical machine, comprising: a brush; a stem having first and second ends, said first end being connected with said brush; spring means pressing said brush against contact means of the rotor of said electrical machine; a brush holder supporting said brush; a current supply bar engageable with said brush holder by receiving a portion of said holder therein; means for effecting replacement of said brush during operation of said machine including a sleeve made of an electrically insulating material mounted at least partly about said brush holder, said sleeve having a first end portion detachably connected to said current suplply bar with adjustment so that said portion of said brush ho der recelved m said current supply bar is pressed against said current supply by connection of the sleeve to said bar; and means for selective raising of said brush from the contact means of said rotor, the brush-raising means being made of an electrically insulating material and being spring-mounted on said stem, said sleeve having a second end portion through which said brush-raising means freely passes, said second end portion of said sleeve having means at the edge thereof to hold said brush-raising means thereon when said brush is to be replaced, whereby said sleeve and said brush holder can be separated as a unit from said current supply bar.

2. A brush unit as claimed in claim 1 wherein said brush holder has an end opposite said brush witha stop member thereat against which said brush-raising means abuts and it supported in the operative state of said contact brush unit, whereby to prevent accidental loosening of said sleeve with respect to said brush holder, a resilient means acting between said portion of said brush holder received in said supply bar and said sleeve to provide electrical contact between said current supply bar and said brush holder when said brush-raising means is retained in the operating position thereof.

3. A brush unit as claimed in claim 2 wherein said resilient means comprises an annular member encircling said brush holder.

4. A brush unit as claimed in claim 1 comprising an element on said stem which lowers together with said stem as said brush wears in operation, said element abutting against said brush-raising means when said brush is worn to a limited extend to prevent any further lowering of said brush.

5. A brush unit as claimed in claim 4 wherein said brush raising means comprise a tumable element which is slidable in said sleeve and is retracted from said sleeve and turned to engage the means at the edge of the sleeve to be held thereon and fixedly secure the said brush and holder in said sleeve.

6. A brush unit as claimed in claim 5 wherein said current supply bar is threaded to said sleeve, said brush holder including an external ring engageable by said current supply bar. 

1. A contact brush unit for an electrical machine, particularly, for a slipring electrical machine, comprising: a brush; a stem having first and second ends, said first end being connected with said brush; spring means pressing said brush against contact means of the rotor of said electrical machine; a brush holder supporting said brush; a current supply bar engageable with said brush holder by receiving a portion of said holder therein; means for effecting replacement of said brush during operation of said machine including a sleeve made of an electrically insulating material mounted at least partly about said brush holder, said sleeve having a first end portion detachably connected to said current supply bar with adjustment so that said portion of said brush holder received in said current supply bar is pressed against said current supply bar by connection of the sleeve to said bar; and means for selective raising of said brush from the contact means of said rotor, the brush-raising means being made of an electrically insulating material and being spring-mounted on said stem, said sleeve having a second end portion through which said brush-raising means freely passes, said second end portion of said sleeve having means at the edge thereof to hold said brush-raising means thereon when said brush is to be replaced, whereby said sleeve and said brush holder can be separated as a unit from said current supply bar.
 2. A brush unit as claimed in claim 1 wherein said brush holder has an end opposite said brush with a stop member thereat against which said brush-raising means abuts and is supported in the operative state of said contact brush unit, whereby to prevent accidental loosening of said sleeve with respect to said brush holder, a resilient means acting between said portion of said brush holder received in said supply bar and said sleeve to provide electrical contact between said current supply bar and said brush holder when said brUsh-raising means is retained in the operating position thereof.
 3. A brush unit as claimed in claim 2 wherein said resilient means comprises an annular member encircling said brush holder.
 4. A brush unit as claimed in claim 1 comprising an element on said stem which lowers together with said stem as said brush wears in operation, said element abutting against said brush-raising means when said brush is worn to a limited extent to prevent any further lowering of said brush.
 5. A brush unit as claimed in claim 4 wherein said brush raising means comprise a turnable element which is slidable in said sleeve and is retracted from said sleeve and turned to engage the means at the edge of the sleeve to be held thereon and fixedly secure the said brush and holder in said sleeve.
 6. A brush unit as claimed in claim 5 wherein said current supply bar is threaded to said sleeve, said brush holder including an external ring engageable by said current supply bar. 